Clinical Thromboembolism Program

The Clinical Thromboembolism Program (CTP), led by Sam Schulman (seen at right), performs research into optimal prevention, diagnosis and treatment of patients with thrombotic problems, translating current research into clinical practice.

Note: for profiles of our CTP Faculty members, please see the CTP Profiles below and click on each photo.

The members of the regional Clinical Thromboembolism Program (CTP) of McMaster University are represented at all sites of Hamilton Health Sciences as well as St. Joseph’s Healthcare. The group is involved in citywide, national and international clinical trials.

Research conducted includes non-invasive methods for diagnosis of deep vein thrombosis and pulmonary embolism, optimal anti-coagulation treatment in cancer and non-cancer patients, the role of anticoagulants as anticancer agents, the clinical role of testing for hereditary and acquired thrombophilias, counseling of patients at risk for thrombosis, prevention of venous thromboembolism in patients with orthopedic surgery, trauma, artificial heart valves etc. Research carried out by this group interfaces in many areas; for example, the interaction of cancer and thrombosis; associations between venous and arterial thromboembolism; bleeding complications and survival of patients with cardiac disease etc.

In addition to venous thromboembolism, several members of the group are increasingly involved with research into arterial thrombosis. In both the venous and arterial thrombosis areas, research is expanding into gene and environmental links to pathogenesis, which Dr. Sonia Anand is leading.

Studies focusing on thrombosis prevention in orthopedic patients, or diagnosis and treatment of thrombosis in cancer patients, primarily involve investigators at the Henderson site. Outcome studies, such as those dealing with the risk of recurrent thrombosis or long-term complications of thrombosis, are conducted citywide or as part of national or international trials.

The health outcomes research has been strengthened by the recruitment of Dr. Frederick Spencer from University of Massachussetts, with which he continues to collaborate, and Dr. Alex Spyropoulos from Lovelace Institute in New Mexico. Dr. Spencer’s research is also increasingly focused on the associations between venous and arterial thromboembolism.

New areas of research that the CTP is about to increase its efforts in are knowledge translation, health outcomes research, application of new diagnostic modalities, strategies to simplify treatment with oral anticoagulants, integration of patient preferences in decisions on anticoagulant therapy, cerebral thrombosis in the developing world, alternatives for prophylaxis against stroke and systemic embolism in patients with mechanical heart valves, association between thrombophilic defects and pregnancy complications as well as prediction of appropriate duration of anticoagulation in patients with venous thromboembolism.

Several investigators in the group (Jeff Ginsberg, Shannon Bates, Clive Kearon) have a solid background in studies on diagnostic strategies in venous thromboembolism. We plan for expanding research into new diagnostic modalities that come as a result of better access to new imaging technology such as 64-slice CTs and MRI and highly qualified professionals in the field of diagnostic imaging with expertise with these techniques.

Cerebral vein thrombosis is particularly common in the developing world but poorly investigated. With the global network of PHRI this is now feasible for investigation of etiology, diagnosis and treatment.

Patients with mechanical heart valves are traditionally treated with vitamin K antagonists for prophylaxis against valve thrombosis, stroke and systemic embolism. The initial “bridging” treatment after open-heart surgery before warfarin becomes fully therapeutic is poorly evaluated. Together with Dr. Richard Whitlock, Cardiac Surgery, we are involved in a multicenter evaluation of the safety of different options. The Thrombosis Service at Hamilton General site will also be an important hub for the first study on an alternative to warfarin – dabigatran - for patients with mechanical heart valves.

Treatment with vitamin K antagonists is complicated and for some patients very demanding. Current and planned trials aim at demonstrating regimens that reduce resource utilization and often are easier and more convenient for the patients. These are phase II trials, but if successful, the phase III trials will require larger networks and a strong methodology support. Studies addressing the optimal management of warfarin after major bleeding are crucial to respond to frequently posed questions by clinicians. One study, addressing the optimal interval until resumption after intracranial hemorrhage has been completed and other, similar topics are currently being addressed.

Several of the CTP members (Sam Schulman, Clive Kearon, Jeff Ginsberg) have played a leading role in the research on optimal duration of anticoagulant treatment after venous thromboembolism. There are still many unresolved questions here and the general practitioner finds it very difficult to make appropriate decisions when to discontinue therapy. A large management study with the use of a marker of activation of coagulation (D-dimer) is currently being performed, involving Canadian, US and also European centers.


The group serves as a model for mentoring, with established investigators providing expertise, time and resources to ensure the success of more junior colleagues. The success of these ventures is evident by the large number of faculty and trainees who have career support from external granting agencies or from local sources and a number of mentoring awards from the Canadian institutes of Health Research.

External collaboration

The members of the CTP have several national and international networks, and at least half of the studies include centers outside of Hamilton. Within Canada the closest co-operation is with Jewish Hospital in Montreal and Sunnybrook Hospital in Toronto. Another network includes several centers in the US. There is also collaboration with Australian and European centers (e.g. Brest [France], Palermo and Varese [both in Italy] and Stockholm [Sweden]). For studies on arterial thromboembolism the group has increasing cooperation with Population Health Research Institute (PHRI), directed by Prof. Salim Yusuf.


The group meets weekly (currently Thursdays 12.30-1.30) at TaARI to discuss “Research in Progress”, often with participation by TaARI’s basic scientists.

Sam Schulman
Sonia Anand
Shannon Bates
Mark Crowther
Kerstin de Wit
James Douketis
John Eikelboom
Alfonso Iorio
Jeffrey Ginsberg
Clive Kearon
Wendy Lim
Menaka Pai
Lori-Ann Linkins
Frederick Spencer